Electrical musical instrument



Feb. 28, 1933.

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ELECTRI CAL MUS I CAL INSTRUMENT Filed Aug. 4, 1950 11 SheefLs-Sheet 11 195 204 3&0 511 G 27' 3 v i W 5 d1) e055 Patented Feb. 28, 1933 NlTED STATES MELVIN L. SEVERY, 0]? LOS ANGELES, CALIFORNIA, ASSIGNOR TO THE VOCALSEVRQ COMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORATION OE DELAWARE ELECTRICAL MUSICAL INSTRUMENT Application filed August 4, 1930. Serial No. 472,969.

This invention relates more particularly to a musical instrument having for each of the various pitches of its range or gamut, one or more qualities of tone, each note of given quality being derived from magnetic undulations set up by a moi Zing member, or moving members, provided with wave-producing means. Each of said members is adapted, through co-acting mechanism, to produce at the requisite loudness one of the partials composing the particular note desired, and all the said members are adapted to produce, at their proper relative loud nesses, air vibrations representing all the desired partials of the said tone. These synthesized air vibrations are impressed upon the ear as a tone of the predetermined pitch and quality desired.

An important object of this invention is the production of a relatively small, cheap, and compact musical instrument adapted to produce any desirable musical qualities of tone, orchestral, vocal, or other, and to grade and control the same at will so that a true vocal or orchestral effect may be attained.

Another object of the invention is to provide, in the cheaper grades of the instrument, a means for giving the necessary separate expression to the air and to the accompaniment of a musical selection, through the instrumentality of a single key-manual.

Another object of the invention is to provide sensibly fundamental tones having the eighty-four pitches associated with a seven octave scale tunedin equal temperament, the same eighty-four notes being used not only for the pitch-giving primes of all of the notes of the instrument, but also, suitably proportioned as to loudness, for all of the other partials which produce the many varied qualities or timbres of the instrument. This is what I denominate my borrowing system, and I use it here because of its extreme simplicity and cheapness of construction, coupled with a musical efiiciency remarkable in so small and inexpensive an in strument. In more elaborate instruments, however, I prefer to use a non-borrowing system wherein the sounders used as primes are not at the same time used as upper partials,

the smallest feasible number of such practice assuring an even greater musical excellence although it is relatively more expensive and complex.

A still furtherjobject of the invention is the production of an instrument requiring no tuning and practically no up-keep, the parts being simple, durable and inexpensive.

In musical instruments making use of a scale tuned in equal temperament and depending for the musical pitches of such scale upon rotating members producing pulsations, all such pulsations, including those representing the well-known incommensurate ratios subsisting between certain notes of each octave, can be secured with an accuracy sufl'icient for all practical purposes by the employment of six rotating shafts or cylinders for an instrument having a range of seven octaves. More rotating shafts may be used, and I have in some cases used twelve, but for simplicity and cheapness I prefer moving shafts. For this reason I make use of the plan clearly set forth in U. S. Patent No. 1,167 ,663' granted to G. B. Sinclair and G. I. Fiske, and dated January 11, 1916.

As shown herein the invention is embodied in a series of six correctly timed cylindrical rotors or shafts carrying members or timbreforms adapted, with their coacting parts, to produce eighty-four sensibly fundamental tones having the pitches of the notes of seven octaves of the tempered scale. To this end, as will be seen by reference to the aforesaid Patent No. 1,167,663, all my said timbreforms, likethe commutators therein shown, are constructed to produce either sixteen, seventeen, eighteen or nineteen vibrations per revolution, or some multiple thereof.

In the drawings:

Fig. 1 is a front elevation of the more essential parts of an instrument constructed in accordance with this invention;

Fig. 2 is a plan view of the essential portions of the mechanism shown in the lower part of Fig. 1;

Fig. 3 is a front elevation. of a soundboard and associated parts Fig. 4 is a sectional view on the line IV-IV of Fig. 3;

Fig. 5 is a similar view on the line V-V of Fig. 3; I

Fig. 6 is a detail view showing the mechanism for attaching magnet-cores to bridges associated with wooden amplifiers of considerable thickness, and for adjusting said cores;

Fig. 7 is a detail view, taken at right angles to Fig. 6, showing a variant form of mechanism for attaching magnet-cores to amplifiers of metal which are relatively thin;

Fig. 8 is an enlarged end view of a dentated magnet core, showing also the supportin elastic spider therefor;

ig. 9' is a plan view of a portion of a sixteen-toothed member or timbre-form;

Fig. 10 is a plan View of a portion of another type of sixteen-toothed timbre-form;

Fig. 11 is a side elevation of a key of the key-manual and some of its associated parts;

ig. 12 is a plan view showing a detail of the contact block of Fig. 11;

Fig. 13 is a detail view showing the adjustable, flat, contacting member of Fig. 11;

Fig. 14 is a sectional end view of the tappetrail of the instrument;

Fig. 15 is a front view showing the more essiential details of a portion of the tappetra1 Fig. 16 is a detail view from above, of the tappet contact finger block of Fig. 15;

Fig. 17 is a detail View of the part 126 of Fig. 15;

Fig. 18 is a diagrammatic view of the tremolo mechanism;

Fig. 19 is a face view of a portion of the multi-pointed relay system;

Fig. 20 is an end view showing the essentials of a single relay-unit, the obstructing panel being removed;

Fig. 21 is a front elevation of the relay system of Fig. 19;

Fig. 22 is an end elevation of a double type of relay which permits certain economies in construction Fig. 23 is a rear elevation of certain parts of said relay;

Fig. 24 is a plan View showing the essential parts of a single mult-i-fingered partialrocker;

Fig. 25 is an end elevation of certain details of the partial-rocker mechanism;

Fig. 26 is a rear elevation showing the manner of stacking the multi-fingered partial rockers seen in Fig. 24;

Fig. 27 is a side elevation, partly diagrammatic, showing the pedal expression-control;

Fig. 28 is a rear view of said expressioncontrol, showing the two multi-contact pedal sections, their coacting brushes, and the disposition of the pedal rods of the three pedals;

Fig. 29 is a diagrammatic view of the switching system for placing the bass and the treble portions of the key-board under control of separate pedals, at will, or controlling both sections by either pedal;

Fig. 30 is an end elevation of part of the multi-fingered resistance-system actuated by the pedals, showing the relation of the stacked switches of one of the two units or groupings thereof;

Fig. 31 is a front elevation of a portion of said resistance-system;

Fig. 32 is a partial plan View showing more clearly certain portions of said resistancesystem;

Fig. 33 is a wiring diagram showing the electrical placement of the various parts of the instrument in a manner which enables the circuits to be readily traced;

Fig. 34 is a diagrammatic view likewise showing the electric circuits for various parts of the instrument;

Fig. 35 is another diagrammatic view of certain electric circuits including both the operative and the speaking system as in the case of Fig. 34; v

Fig. 36 is a front elevation of the instrument showing the placement of pedals, kneeswells, tappets, etc.

As is well known in scientific. music, the quality of a musical tone, or its timbre, is dependent upon its component partials and their relative prominence. These partials normally are, to all intents and purposes, whole-number multiples of that particular partial among them known as the prime or pitch-determining partial of the tone. It is not so commonly known, however, that a seven-octave instrument tuned in equal temperament has all the partial'vibrational numbers to and beyond those partials which are of any especial importance in the production of musical tone qualities, represented to a degree of perfection quite sufiicient for all practical purposes. Therefore. by producing, combining, and controlling at will eighty-four fundamental tones, used for primes and all other partials, I am able to produce all desired musical timbres with a simplicity of mechanism which is indeed remarkable.

The first six partials are those which are important in musical timbres, but in this instrument I use to and including the tenth, taking, however, a sub-octave in place of the seventh partial, as I have found a graded lower octave more useful than the seventh partial. I do not, of course, limit myself to any particular number of partials, but the number here used gives most excellent results for an instrument of this capacity. Neither do I limit myself to the number of partial gradations herein shown, as the more varieties of strength each partial has, the greater the number of tone qualities possible to the instrument. It is merely a matter of expense. It is desirable that each important partial should have at least two to three different loudnesses, but in most cases I have 1 not here illustrated so many lest the wiring be too complex to be easily understood.

The eighty-four simple tones to which I refer in connection with this invention are produced as set forth in Letters Patent No. 1,464,729 granted to me August 14, 1923, the pulsation-producing members, whether each be integral or laminated, educing in the present instance, only one periodicity characterizing a simple or fundamental tone.

Inasmuch as the pressure of a key of the key-manual does not directly actuate lthe tone-producing magnet, such magnet being operated through its associated relay, I find it convenient, for more ready comprehension, to dividethe instrument into two main systems designated respectively the operative system and the speaking system, the keymanual of course belonging to the former system, and shall describe the same in the order mentioned.

The more. essential moving parts of the instrument with their co-acting members are 25 shown in Fig. 1, the belting and some other details being omitted to avoid confusion. In said figure the numeral 1 designates one of the three rotor-carrying cylinders or shafts of the bass section of the instrument, this shaft being associated with all of the notes G#, A, A#- and B of the lower three octaves of the instruments compass. Similarly, 2 designates one of the three treble cylinders or shafts, that shown being the one associated with the same notes of the four higher octaves of the instruments compass. Pulleys 3 and 4 of like size are provided for driving said shafts. Sound-boards 5 similar to those of Figs. 3, 4 and 5 are each provided with magnet-rails 6 from which magnet-cores 7 are seen protruding in co-action with their respective pulsation-producing members 8. Openings 9 between the sound-boards of the bass section of the instrument (Figs. 1, 4 and 5) serve, in the case of each pair of boards, to ventilate the chamber between them and release the sound-waves created therein, the bass section of the instrument carrying in each frame two parallel boards as more clearly shown in Figs. 3, 4 and 5. The soundboards 5 are mounted in slidable frames 10, the frames being normally fastened together as at 11 so that they may slide as a double unit in runways 12 provided for that purpose and for holding the boards securely in position. The six shafts or cylinders such as 1 and 2 are each stepped upon a ball at their lower ends, and are each surrounded there by a ball-bearing indicated at 13, while similar ball bearings serve the upper ends of said shafts as indicated at 14. To quiet the slight noise of the moving parts, they are placed at the bottom of the instrument as shown, a sound-deadening partition 15 formed in sections so that it may be easily removed when desired, being also provided. The two wider sections of this partition between the bass and treble sections, and the narrower end sections 15, separate the driving mechanism from the music-producing section; of the instrument, which is directly above said mechanism. On either side of each set of .three shafts is one of these narrow removable sections 15 of said partition, the two sections separating on the center lines of the three shafts, and each carrying half rings of felt adapted to close around the shafts when the co-acting sections are in position, thus leaving the shafts quite free while preventing the escape of sound form below. The two wider sections of the partition are also provided with felt packing further to assist in rendering the portion of the instrument containing the moving parts, sound-proof.

A large pulley 16, twenty inches in diameter in this case, carries upon it a smaller pulley 17 a pulley l8 grooved to receive a round belt being mounted on the pulley 17. The pulley 18 serves to give motion to a pulley 19 associated with the tremolo mechanism, the functioning of all of which will be more clearly set forth hereinafter. As will also be more fully explained later, the function of the large pulley 16 is to reduce the rotative speeds of the three bass shafts to onequarter that of the speeds of the shafts which control the corresponding notes of the treble sections. The pulley 16 also carries suitable governing apparatus installed within a receptacle 20 (see Fig. 2) coverable to exclude dirt and dust. The source of electric energy 21, switch 22, conducting rings 23 and 24, and brushes 25, 26 render operative a speed-regulating finger later described. As seen in Fig. 2 the pulley driving the middle shaft of each group is out of plane with and underlies or overlaps the smaller pulleys of the proximate shafts, thus permitting close arrangement of the three shafts of each group. This is necessitated by the large diameter of these pulleys, 1'10 ten inches in the presentinstance.

As stated, the shafts 1 and 2 are for convenience called by the octave-name of the lowest note they carry, but it is to be borne in i mind that each of said shafts carries notes of four octave-names, the G# shaft of the bass section, for example, carrying all of the notes G#, A, A#and B found in the lower thirtysix notes of the key-manual corresponding to what I term the bass section of the instrument. 27 and 28 (Fig. 2) indicate respectively the C-shafts of the bass and treble sections, While 29 and 30 designate the E-shafts of said bass and treble sections. 31 and 32 designate the pulleys for the C-shafts 27 and 28 of the bass and treble sections, these pulleys being ten inches in diameter, while 33 and 34 indicate the pulleys driving the two E-shafts 29 and 30 of said bass and treble sections, the pulleys 33 and 34 being in this instance 7.9370 inches in diameter. Idlers 35, 36, 37 in the treble section, and 38, 39 in the bass section serve to turn the two belts 40, V 41 operating the bass and treble shafts rel spectively. These belts must be of even thickness, as nearly alike in flexibility as possible, and of the same texture throughout. When made of leather not only should the hair side always be made up into the .belt one 10, way, as is customary, but the idlers should be so placed and the belts so planned, that only the one side of the belts ever faces the pulleys, since if the belt keeps shifting from hair-side to flesh-side, these changes will be heard in the tones produced by the instrument. If leather is used for the belts they should be carefully worked down on a miller to exact thickness throughout.

It will be noted that idler 36 is slidable so that it may be adjusted for the purpose of producing and maintaining the requisite tension of the treble belt 40, while idler 38 is similarly adjustable with regard to the belt 41 of the bass section. A motor 42 of 1160 R. P. M. is connected to a speed-regulating mechanism 43 carrying a driving pulley 44 of 4.1810 inches diameter serving to propel the six shafts of the instrument at their proper constant speeds despite line fluctuations of the current. These speeds are approximately as follows in the treble section: For the shaft carrying the notes C, C#, D and D#, 485 R. P. M.; for the shaft carrying the notes E, F, F# and G, 611.0617 R. P. M.; and for the shaft carrying the notes G#, A, A# and B, 769.8895 R. P. M. In the bass section the speed of the shaft carrying the notes 0, C#, D and Dzfi: is 121.2500 R. P. M.; the speed of the shaft carrying the notes E, F, F# and 49 G is 152.7654 R. P. M.; and the speed of the shaft carrying the notes G#, A, Ail: and B is 192.4723 R. P. M.

Tracing the path of the treble belt it will .be seen that it passes from the top of.

driving pulley 44 to idler 35, whence it passes about pulley 45 on the treble Gil: shaft; thence to the rear side of he adjustable idler 36; thence to the front of C-shaft pulley 32; thence to the rear side of idler 37; thence to the frontof the E-shaft pulley 34; from the rear of said pulley 34 to the rear of pully 16; and from said pulley 16 to the under side of driving pulley 44, thus completing the circuit. The diameter of the pulleys 45 and 46 is approximately 6.2996 inches. The belt circuit for the bass section of the instrument is as follows: From pulley 17 which is fast to the large pulley 16, belt 41 passes to the further or rear side of the bass Git shaft pulley 46; thence about said pulley 46 and to the front of the adjustable idler 38; thence to the rear of C-shaft pulley 31 atlaence to the front of idler 39: thence to the rear of bass E-shaft pulley 33; thence about said pulley 33 and back to the front of pulley 17, thus completing its circuit.

The speed-regulating mechanism 43 will not be here described in detail since it forms the subject-matter of my c o-pending application Serial No. 371,211 filed June 15, 1929,

but it should be stated that it is rendered oppin 51. The'finger 47 has a silver or tungsten tip which is adapted in action to contact with the resistably rotatable silver disk 52, the angular position of which may be changed should any pitting thereof occur. This speedcontroll1ng apparatus is, as stated, contained 1n the receptacle 20. The contact members 47 and 52 are insulated from each other and both are preferably insulated from the frame, but one at least of said members must always be so insulated. I have shown them both insulated from the large pulley 16 and therefore from the frame, as this procedure renders accidental short circuits less likely. To this end separate brush contacts 25 and 26 are provid ed for each polarity of the current, as seen in Fig. 1. From the negative pole of currentsource 21 a wire connects with flexible contact-finger 47, and when the speed of pulley 16 rises sufficiently to move said finger 47 into contact with disk 52, the current passes through said wire and a wire 53 to one pole of a relay-magnet 54. The circuit as shown in Fig. 2 omits the conducting rings 23 and 24 and their co-acting brushes 25, 26 shown in Fig. 1. From the other pole of relay-magnet 54 a wire passes to the positive pole of the source of electrical energy 21, thus completing the finger and relay circuit. A wire 56 recelves positive current from source 21, which it passes to one pole 57 of the relay switch operated by magnet 54. The other pole 58 of said switch is electrically connected by wire 59 with one pole of an inductive clutchrnagnet 60, the other pole of said magnet belng carried by the supporting frame 61 and connected by a wire 62 with the negative pole of current-source 21, thus completing the circuit energizing the clutch-magnet 60.

The speed-regulating mechanism 43 con tains gears which are so arranged and proportioned that when driving pulley 44 is turning at the predetermined and desired speed, there is little or no motion between these gears. To attain this condition of affairs, however, the clutch-magnet 60 must oppose a resistance to the free motion of the copper disk or contact between magnet 60 and the disk, each time said clutch-magnet is energized by the opening of the contacts in the finger-box 20 carried by pulley 16. This action deenergizes relay magnet 54, permitting the spring-actu'ated closure of the relay points and the energizing of the clutch-magnet, with the result aforesaid. If the copper annulus 63 is prevented from rotating, the mechanism will speed up materially beyond) its requisite velocity, and if it is allowed to revolve without hindrance, the speed of the mechanism;

will fall materially below the necessary velocity. The finger 47 being, however, exceed- .inglysensitive to speed changes, a practically uniform and correct speed is maintained even when the motor speed varies, and this without any appreciable movement of the contained gear-mechanism. I sometimes employ a steady, inductive breaking action upon copper annulus, in addition to the intermittently acting clutch-magnet, where T find 1t desirable to make the clutch magnet act through a narrower range of speeds, but as this in no way changes the-principle of action of the speed-regulator, l have not shown it. Moreover, this mechanism is described in detail in my co-pending application before noted.

The sound-board 5 shown in Fig. 3 is sultably ribbed on both its surfaces (see F g. 5),

and beneath it is another board, not V1Slbl.,.

but which is actuated by amplifiers 64c, 65 and 66 through the agency of bridge-blocks 67 projecting upwardly through the openings in the upper board. These three amplifiers, bridge-blocks, and lower invlsible board serve three notes of the lowest octave of the instrument. All of the notes of this octave are of less than sixty-four vibrations per second, and so require a relatively thin board for the best results. The amplifiers 64:, 65

and 66 are of wood'and their front ends are secured by dowels to their associated bridge: blocks, their rear ends being flexibly doweled to a block supported rigidly by a casting 68 or 69, as the case may be, the castings 68 being secured to the top and bottom, respectively, of the sound-board frame, while the casting 69 is secured to the sides of said frame and forms a free strut across the active portion of the sound-board somewhat below its median line. Metal amplifiers 70, their front ends screwed to bridge blocks upon the board 5 and their rear ends securely fastened to castings 68 or 69, serve notes above the lowest octave of the instrument.

The magnet-rails 6 are adapted to receive magnets in the openings shown in Fig. 4. These rails, in this case, will each house three speaking magnets, a magnet in each rail serving one of the amplifiers 64:, 65 or 66 to which it isopposed, and the remaining magnets of each rail serving the amplifiers 76 associated with said magnets. The magnet rails are secured at their ends to the vertical sides of the board frames, as more clearly shown in Fig. 5. 71 indicates the sound-board before referred to, serving the notes of the lowest octave of the instrument, this board being much thinner than the board 5. The board 71 is also ribbed on both sides (see Fig. 5), and provided on its inner side with the bridgeblocks 67 reaching upwardly through the thicker sound-board to take the operating dowels of the bass amplifiers 64:, 65 and 66. These bridge-blocks are shown securely glued to the base board 71 between ribs from which they secure additional attachment (see Fig. 4:) Wooden blocks 72, preferably of maple and securely fastened to the castings 68, each receive the two flexible dowels extending down into it from the rear end of its associated bass amplifier, thus permitting the magnet-cores 7 of Figs. 1 and 5, which in practice pass through the openings 7 3, to deliver their impetus through the bridge-blocks to the bass board 71. The mounting and action of the amplifiers serving notes above the lowest octave of the instrument is similar to that just described. A bridge-block 74: secured between ribs of the upper board has the curved front end of said amplifier secured to it.- This amplifier is shown as wavy, and the curve at its outer end where it is screwed to its bridge-block, gives it the required freedom of movement. These metal amplifiers should be made progressively weaker or more flexible, fro'm'their rear to their front ends, either by progressive decrease in width, in thickness, or both. The wave-form of the amplifiers is convenient but not essential.

Three speaking magnets 75 are shown in Fig. 5 housed within one of the magnet-rails 6, said rail being screwed at each end to the boa'rd-frame. As seen in this figure the magnet-cores 7 have their lower ends fastened to flexible spiders 77, and extend upwardly and freely through a central tube in each helix of wire,-said cores being in practice, though not so shown in Fig. 5, secured at their upper ends to their respective amplifiers by means more clearly illustrated in Figs. 6 and .7. For the purpose of more clearly showing the windows and ledges 77 of the median strut or casting 69 which is adapted to accommodate the metal amplifiers of the horizontally median section of the upper board, the amplifiers 70 are not seen in Fig. 5 and the magnet-cores 7 are broken 0d at their upper ends. A j ack-knife switch 78 is adapted to make and break electrical connection with all the magnetsof its board-frame, nine in number in this case. 79 indicates a segment of a revolving rotor showing its relation to the dentated core above. it. While the instrument here shown employs a soundingboard form of resonating member, it is to be understood that the invention is not limited thereto, or to any particular type, as any suitable sound enlarger or resonator may be used, one of the very best forms of resonator being that making use of a more or less confined definite volume of air carefully adapted to the pitch it serves.

. Figs. 6 and 7 show details of the mechanism for attaching the amplifiers to their actuating magnet-cores 7, Fig. 6 illustrating a wooden bass amplifier of considerable thickness. A flexible tongue 81 of metal is pinned and soldered firmly into the upper end of core 7 so that it will not rattle. To the upper end of flexible tongue 81 is secured a threaded member 82, also pinned and soldered.l A shouldered nut 83, longitudinally slotted as shown at 84: to receive a pin 85 permittinglongitudinal but not rotative mo tion, is threaded upon the member 82. Pin 85 is carried by thumb-wheel 86, said wheel serving to turn nut 83-rotatively while permitting its free movement longitudinally. This arrangement affords easy ad]ustment of the magnet-core to and from its co-acting rotor without disturbing the amplifiers correct relation to its board, an operation which permits excellent voicing of the instrument. A metallic plate 87 is screwed to the wooden amplifier 80, a retaining nut 88 serving to maintain adjustments when once made. To change the distance of any magnet-core 7 from its rotor, nut 88 is slightly loosened so as to take thepressure ofi. thumb-wheel 86 which is then turned to the required position for the desired adjustment, after which nut 88 is again tightened to maintain that position. The spiders 77 at the lower ends of the cores prevent rotation of said cores.

Fig. 7 shows a variant form of the attachment illustrated in Fig.6, adapted to the metal type of amplifiers used for notes above the lowest octave, the flexible tongue 81 (viewed in this case at right angles to the position of Fig. 6), threaded member 82 and retaining nut 88 being identical with the parts of Fig. 6. A shouldered'member 89 with a free unthreaded hole issecurely fastened to the metal amplifier 7 O, and below this member is a threaded thumb-wheel 90. To make an adjustmentthe retaining nut 88 is loosened and the thumb-wheel 90 turned one way or the other, as the case may be, thereby permitting the core 7 to take a somewhat different position, after which the nut 88 is tightened to maintain the new adjustment. The function of the flexible tongue 81 is to permit the free movement of the amplifier during its vibration, as a coreheld against transverse movement by both amplifier and spider would be seriously hampered in its longitudinal activity.

In U. S. Patent No. 1,464,729 granted to me August 14, 1923, I show a core of a speak-' ing magnet adjustably fastened directly to the bridge of a sound-board, and I could adopt such procedure in this instance in cases where a tone of special brilliance is desired. Usually, however, I prefer the arrangement shown in Figs. 3, 4, 5, 6 and 7, in which the amplifiers, of whichever type used, materially round the shape of the wave, making it less brilliant and more pleasing to the ear. Where the weight of the core, added to that of the amplifier, does not secure this effect to a sufficient degree, I sometimes add a further weight, as a lead washer 91 (Fig. 7), located at any suitable point along the length of the amplifier. I also use this same method at times when the amplifier system is found to be too rigid for the best results, and I wish to make it plain that I consider all these and equivalent expedients quite within the scope of my invention.

The construction of the spider 77 shown in Fig. 5 is illustrated in Fig. 8, where 92 designates the enlarged, double-toothed head of a magnet core to which the central disk 93 of the four-armed spider is securely fastened, the extremities of its arms being secured to a larger disk 94. In practice the disk 94: is centrally disposed over its associated speaking magnet 75, and is suitably secured to the magnet-rail 6 housing the same, as shown in Fig. 5. It will be noted that the magnethead 92 has a space between its teeth much greater than the width of a tooth, and the rotor segment 8 shown in Fig. 9 illustrates a similar characteristic with regard to its teeth and the core-head opposed to them.

The sixteen-toothed pulsation-producing member or rotor 8 is shown in detail in Fig. 9, where a segmental portion thereof is seen having all the teeth except the right-hand one designated 8 shown alike. This odd tooth, unlike its companions, has its radially outermost surface either flat as shown, or concentric with the center of the rotor, while the outermost surfaces of the remaining teeth form arcs of a much smaller circle. A double-toothed magnet-head 95 is opposed to the member 8, the centers of its teeth being the same distance apart as the teeth of the segment 8. The outer ends of the teeth of magnet-head 95 are shown as having almost the same curvature as the circumference of the pulsation-producing member or rotor opposed to them. This arrangement secures an attraction and let-go of the magnet-core making for brilliancy of utterance and sharpness of articulation, characteristics not favored by any magnetic hold-over. The type of tooth shown at 8 yields a slightly different result, yet one that may be useful in some cases. It is to be remembered that so long as a key of the manual is pressed its associated speaking magnet is normally energized, so that lines of force are streaming toward both the teeth and the spaces of an opposed member or rotor. Accordingly, it is desirable that care should be taken to procure a sarily somewhat sma1l, it is possible to use as many as five or six core-teeth, spacing them as before and materially farther apart than their own widths, in both rotor and core-head. Indeed, in the very highest notes, the teeth of both cores and rotors may be relatively sharp at their outer edges. This use the lower end of said spring bein of multiple core-teeth and the somewhat wide spacing of all teeth, is a most vitalmatter where maximum eihciency and b-rilliancy are desired. It will be noted that the outermost portions of the teeth of multi-toothed coreheads such as 95 preferably fall in an arc of practically the same circumference as that characterizing. the similar portions of the pulsation-producing member or rotor, thus making. for maximum eficiency by permitting more intimate co-action between rotor and core without danger of contact.

Fig. 10 shows a segmental portion of a sixteen-toothed pulsation-producing member or rotor 8 adapted to produce a graver and less brilliant type of tone than that characterizing the rotor of Fig. 9. Iln thisinstance the letgo of the rotor teeth is more gradual and less complete than shown in Fig. 9, with the result that the tone is smoother and less insistent. l have shown these two widely divergent types, but it is to be understood that 1 do not confine myself to either of them, for l may use anything between them as particular occasions may demand, or ll may still further accentuate the characteristics of either of the rotor segments shown in Figs. 9 and 10, for l have complete command of the form of the wave produced in the air, as well as of its loudness, its pitch, and all of the functions associated with its use as a partial in a compound tone.

Referring now to Figs. 11, 12 and 13, a portion of the operative system as contradistinguished from the speaking system will be described. 96 designates a key of the key-manual resting upon the somewhat conventional ltey-bed, and held in position by the usual vertical pins 96" passing into broadclothed holes formed in the keys. A. projection having a screw-eye passed through it, and an adjusting leather nut, are provided at the rear of each key 96 for the purpose of securing and tensioning a key-elevating spring 97, looped about a slanting, notched dowel 98 g ued into the rear of the key-bed. A felted key-strip 99 limits the upward action of the keys under the urgency of spring 97. A Inulti-contact block 100, seen more in detail in Fi 12, is

5 screwed to the key-bed beneath each ey, the

block being conveniently grooved to fit over the longitudinally-extending positioning strip 101. This ,strip also serves to keep pressed upwardly, in passive position, the

wire tongues 102 serving as contact members. 103 designates a wiring-strip, current being supplied through the cable 104. A continuous metal strip 105 serves as a common lead or return, as the case may be, since it is immaterial which purpose it serves, if other conditions are suitably adjusted. A similar contact tongue 102 of each key-block is soldered to the strip 105. lhe other tongues 102 of key-block 100 are joined to individual wires, which pass into cable 104, said cable being connected with switches and relays later described.

Beneath each key'96 and screwed thereto somewhat forward of its center, is a flexible contact-bridging tongue 106 of metal, seen in perspective in Fig. 13. One end of said tongue is bent downward and shod at its lowermost portion with a strip 107 of silver, adapted to contact, when in action, with the silver tips 102 at the forward ends of the wire tongues 102. An adjusting screw 108 is passed through each key 96, the lower end of said screw being shouldered or reduced in diameter to pass through a hole in the metal tongue 106, thus serving to hold said tongue against sidewise movement relative to the key. llhe head of screw 108 is preferably seated in a recess in the upper side of key 96, and the shouldered lower end bears upon the tongue 106,50 that upon advancing the screw the shoulder will bear upon and depress the tongue 106. Upon backing the screw the tongue will be permitted to rise by reason of its resilience. The contact wires 102 are bent upwardly at their right-hand ends to facilitate wiring into the cable 104: or on to the continuous strip 105 Qne similarly disposed wire of each block 100 is joined to said strip. l'n Fig. 11 this connection is parted to avoid confusion in the drawing, and the open ends thereof being indicated by the wires 109 and 110.

In Fig. 12 the multi-contact block 100 is seen from its under side to show the grooves which extend through somewhat more than half the thickness of said block as seen in Fig. 11, these grooves serving to house and protect the four wire tongues 102 of each block. i

pear at its rear end beyond the wide transverse groove 111, have no function and could be dispensed with if the blocks were molded instead of sawn, as might well be the case. A hole 113 receives a screw by which the block 100 is fastened to the key-bed under its appropriate operating key.

It has already been stated that one of the four wire tongues 102shown as associated with each contact block 100, is connected to the continuous strip 110 used, say, as a return, and this tongue may well be that farthest removed in Fig. 11, or nearest the bass end of the instrument. In this case the next or second of these tongues would be connected by an individual wire through the a cable 104, to one pole of the magnet operating the relay bearing the number of the note with which it is itself associated, the other pole of said magnet joining a source of electric. energy and the circuit being completed" through the commoncontinuous metallic return-strip 105, the leftmost tongue 102, and the-contact-bridging tongue 106. In the case of the third wire tongue 102, the purpose of which is to couple up an octave, its connecting wire runs to one pair of contacts of a multiple switch capable of opening or closing the circuits of all these third wire tongues connected to it. From the co-acting contact of this third pair, a wire runs to one pole of the relay magnet bearing a number higher by twelve than that of the manual key with .which said third wire tongue is directly associated. From the other pole of this lastnamed relay magnet the circuit is essentially the same as in the case of the previous or second wire tongue. The last, or fourth wire tongue 102, serves to couple down an octave,

for which purpose it is connected by a wire with one contact of the appropriate pair of contacts in a separate couple-down multiple switch essentially like that mentioned for coupling up. From the co-acting memberof this fourth pair, a wire runsto the relay" magnet bearing a number less by twelve than that of the manual key directly over the fourth wire tongue 102, after whichthe circuitis substantially as in the similar cases. It will be seen, therefore, that to couple up or couple down an octave requires only the closure of the appropriate multiple switch or circuit-making and breaking device. If

this be left open, all its corresponding or associated wire tongues remain dead and inoperative.

Fig. 14 shows a cross section of the tappetrail forming part of the speaking system. said rail being seen in its correct placement with regard to the instrument as a whole, in Fig. 36. The two longitudinally split halves of the tappet-rail are indicated at 114 and 115, each portion of said rail being secured to the member 116 by screws. the portion 115 is also secured to the portion In addition 119 driven into the portion 114 of the tappetrail, and having its other end supported against downward pressure by a ledge 120, serves as a pivot for the rocker 117. 121 designates a tappet contact-finger block in and above which are seen two of its co-acting fingers, the contact-bridging member 122 of Fig. 15 being omitted in Fig. 14 for clearness of illustration. A cable 123 carries the wires of the tappet system.

Fig. 15 shows the tappet-rail of Fig. 14 with the front portion 115 removed to exhibit the interior construction of said rail, and also illustrates the radial contact-bridging fingers'122 omitted from the previous figure. The median line extending from the tip of each finger 122 throughout most of its length on both its front and rear sides, though the latter cannot well be shown in this view, represents a silver wire soldered to'said fingers to insure a perfect contact with the co-acting members 124 opposing each other, the fingers 122 passing between sa'.d members 124 essentially after the usual manner of the movable member of a jackknife switch. Broadclothed recesses 125 limit the angular movement of each upof each tappet-rocker, the other end of member 126 being elastically supported in and by a tongue-spring 128 fastened at one end and bent to slide slightly at the other. By this arrangement the upper end of the metallic member 126 may be swung, although with considerable resistance, first to one and then to the other side of a vertical diameter of the cylindrical part 117 for the purpose al- "ready'stated. Each contact-finger block 121 carries a plurality of wire contact-fingers 124, the number varying in accordance with the number of partial rockers the particular tappet switch is designed to command. One contact-finger 124 for a return wire is always provided, with at least one additional finger, but there are often many more serving one polarity of as many actuating magnets of the partial rockers later described. These contact-finger blocks 121 are screwed at their ends to the lower part of the front face of the portion 114 of the tappet rail, as clearly indicated in Fig. 15. p p

Fig. 16 is a view from above of one of the contact-finger blocks 121', showing also in dotof the tremolo,

ted lines the shallow underneath grooves for the angularly bent wire contact-fingers 124. It will be noted that there are eleven holes 129 extending from the top of block 121 down into said grooves, the wires 124 being thrust up into these holes and their bent ends seated in the underneath grooves to prevent their escape when the block is screwed into posi tion. The holes 129 are staggered for the two rows of contact-fingers, said fingers being preferably bent at different angles, first other, so that they may adverted to in connection with The knee-swell 130, knee-swell of Fig. 36, is shown in Fig. 18 as passively positioned against a stop 131 by a spring 132 which causes a bifurcated brush 133 having one prong somewhat longer than the other, to rest wholly upon insulation at the right-hand Which, when the knee-swell is operated is traversed by the brush 133. enever the tremolo is actuated, it introduces into the, circiut of all speaking magnets in action, at the will of the player, any desired amount of resistance, while the revolving short-circuiting or shunting commutator 135, driven by a belt passing about the tremolo pulley 19, periodically cuts in and out this inserted resistance, causing a shake in the tone the prominence of which will, for any given passage, depend upon the position of knee-swell 130. The pronged brush 133 is carried by a fiat, slidable bar 136 running in graphited felt bushings, said bar having secured to its leftward end a flexible wire Another connecting Figs. 1 and 2.

by drum 134, this wire 138 being suitably sebox containing said drum by a binding post or equivalent means. A link 139 serves to connect bar 136 with the innermost extremity of rod 140. The resistance shunting commutator 135 comprises three sub perficial metallic portions 141, 142, 143, the brushes 144 and 145 being each adapted to bear successively upon two of the said superficial metallic portions of said commutator. In the position in which they are shown in Fig. 18 the brushes 144 and 145 are, with respect to the revolvable commutator, insulated from each other, but as soon as the metallic portion 143 comes uppermost the brushes will be electrically connected by the bridging action of this portion of the commutator. This is the condition under which the resistance of drum 134 is shunted out during the operation at each half revolutionof commutator 135, while during the other half revolution the current is forced to pass through that portion of the resistance helix which is not cut out by the movement of brush which is the right-hand "slidable bar 133 to the left. The manual keys are indicated at 96 and the speakin magnets at 75, it being understood that in t e diagrammatic, showing of Fig. 18 all possible irrelevant parts are omitted and only the tremolo system illustrated.

A flexible contact spring 146 (Fig. 18) is secured to the left end of the box which houses the resistance drum 134, the left end of the resistance helix and of wire 138 being, secured to said contactspring. To ensure perfect and correctly timed contact, the contacting end of spring 146 is adjusted relative "to its co-acting contact by a screw 147 passed through an opening in the spring. An angularly bent me'mber'148 is secured to the 136, and pushes the flexible. tongue 146 slightly to the right as member 148 contacts with said tongue under the action of the knee-swell spring 132, thus shutting off the tremolo upon the removal of the players knee and cutting out the resistance helix irrespective of the position of the revolving tremolo commutator. As shown in Fig. 18 the tremolo is not in action, and the current passes from source 149 to the key 96 associated with the leftmost of the five speaking magnets 75; thence from the other pole of said magnet by a wire 150 to wire 138; thence to contact spring 146, contact member 148 and wire 137 back to said source 149.

If, now, the knee-swell be moved to the right, brush 133 will come into contact with the resistance helix, the contact members 146, v 148 will open, and the circuit will be as follows with the revolving commutator as shown: From before, to and through the leftmost of the five speaking magnets 75 and wire 150 to wire 138, since the commutator brushes 144, 145 are open-circuited; thence by such portion of the resistance helix as is in circuit, to brush 133, slidable bar 136 and Wire 137 back to source 149. When, however, as occurs a fraction of a second later, the tremolo commutator makes a half revolution bringing the ridging member 143 under the brushes 144, 145, the resistance helix is immediately cut out, as will be ObYiOllSJ Two very-important advantages inhere in this system. First, the tremolo may be instantly operated for even a single note without the use of the hands; and second, it may be used with any desired degree of prominence, there being many cases where a slight tremolo is excellentbut a pronounced one would be very undesirable, while at other times a marked tremolo is quite permissible. So far as I am aware, this gradable tremolo is a new and valuable feature in an instrument of the character here disclosed.

Figs. 19 and 20 are respectively a face and an end View of a portion of a row of single relays. When of the type here shown these with seven relays in each unit. Two of these the source of current 149 as I 

